Square Footage is always a precious commodity in New York City. Values for both residential and commercial spaces are always listed in dollars per square foot. Back in a former life I worked for an architect who specialized in high-end apartment renovations. There was never any extra space, regardless of the apartment size. He equated apartment design to the equivalent of detailing one giant cabinet. Every niche, every corner was precisely detailed to it’s maximum potential.

Along those lines, when planning new residential construction, as well as gut rehabs of existing buildings, owners press designers to minimize the core (stairs, elevators, etc) since these items do not represent square feet that can be sold. In buildings with small footprints the core can take up a significant percentage of the floor plate. The most efficient layouts for such buildings is to limit each floor to one or at most two apartments. With such a layout, corridors are not needed to reach the required egress stairs.

Historically the Building Code has not allowed the layouts to reach their maximum efficiency. Both the 1968 Building Code and the Multiple Dwelling Law have prohibited apartments from opening directly into egress stairs. Because of this restriction, even the designs with one apartment per floor were forced to provide vestibules, serving the function of the corridor, at each entry to the egress stairs.

Although the vestibules needed to be a minimum size they still ate up valuable square footage. Ironically, because they only needed to be the size of an oversize closet, the tendency was for the tenant to be use them as storage areas. So a vestibule that was meant to protect the tenant from smoke and fire turned out to impede the path to egress as it was filled with bicycles, boxes and other closet stuff.

With the adoption of the 2008 Code, things got worse. BC 1013.6 states for R-2 buildings 3 plus stories in height, apartment doors must open into a corridor. It further states that the corridor must have access to both required stairways. So now the building with the single floor apartment needed a corridor connecting two stairs that the Code also requires to be remote from each other. This corridor eats up significantly more square footage than the old vestibule approach.

Some relief is coming via the 2014 Code. BC 1014.4 – Intervening Public Hall in R-2 occupancies now differentiates between high rise and non-high rise buildings which are less than 75 ft tall. BC 1014.4.1, Exception 2 allows both the public hall and intervening public hall to be eliminated in non-high rise buildings if the apartment doors are smoke and draft control doors complying with UL 1784, and the building is sprinklered.

Many on the Code committee tried to have this section applied to a building of any height since it is not uncommon to have high rise buildings with only one apartment per floor. The FDNY representatives on the committee strongly objected. The objections rose from the tactical realities of how fireman fight a high rise fire, where the public halls or corridors serve as the staging area above or below the fire floor.

The compromise reached for high rise buildings is limited but can still be very useful to building designers. BC 1014.4.2 calls for the intervening public hall but provides an exception for a floor that contains only the upper levels of duplex apartments. In that case either a vestibule can be used to reach each individual stair or the vestibule can be eliminated by providing the same smoke and draft control doors allowed in the non-high rise buildings. The FDNY wants to see public hallways at the level where the apartment entries are. In cases where the apartment entries are at the upper level, a determination would need to be filed to eliminate the lower level public hallway.